Method and apparatus for landing well pipe in permafrost formations

ABSTRACT

A method for landing and suspending well pipe strings in wells penetrating subsurface formations including formations adjacent the earth&#39;&#39;s surface particularly susceptible to subsidence, such as permafrost formations or zones, that prevents damage from subsidence. At least one (outer) well pipe is run and set in the permafrost formation and cemented to the permafrost formation. At least one other (inner) well pipe is run and set through the permafrost formation in lower level subsurface formations and cemented only to the lower level subsurface formations below the bottom of the permafrost formation. The entire weight of the inner well pipe is supported on the outer well pipe. In the event of subsequent subsidence of the permafrost formation, the outer well pipe may subside without affecting the inner well pipe. A third inner well pipe is suspendible on and within the inner well pipe without causing buckling of the inner well pipe.

United States Patent [72] Inventor Terrell V. Miller 3 Houston, Tex. [2]] Appl. No. 851,886 [22] Filed 1 Aug. 21, 1969 [45] Patented Feb. 9, 1971 [73] Assignee Esso Production Research Company [54] METHOD AND APPARATUS FOR LANDING WELL PIPE IN PERMAFROST FORMATIONS 20 Claims, 2 Drawing Figs. [52] [1.8. CI 166/285, 166/242, 166/315 [51] Int. Cl E2lb 33/14 [50] Field ofScarch 166/315, 285,242, 302; 175/17 [56] References Cited UNITED STATES PATENTS 2,205,119 6/1940 Hall et a1. 166/315X 2,284,969 6/ 1942 Adkison 166/315X 2,607,422 8/1952 Parks et a1. 166/242X 3,179,528 4/1965 Holmgren et a1. 166/293X 3,347,319 10/1967 Littlejohn 166/242 OTHER REFERENCES Anonymous, Slope Operator Plan Subsidence Fight, Oil and Gas Journal, December 8, 1969, (pages 69- 72) 166- -302 Dier, New Ideas Solve Permafrost Drilling/cementing Problems," World Oil, May 1969, (pages 89- 92) 166- 285 Primary ExaminerStephen .1. Novosad Attorneys-Thomas B. McCulloch, Melvin F. Fincke, John S.

Schneider, Sylvester W. Brock, Jr., Kurt S. Myers and Timothy L. Burgess ABSTRACT: A method for landing and suspending well pipe strings in wells penetrating subsurface formations including formations adjacent the earths surface particularly susceptible to subsidence, such as permafrost formations or zones, that prevents damage from subsidence. At least one (outer) well pipe is run and set in the permafrost formation and cemented to the permafrost formation. At least one other (inner) well pipe is run and set through the permafrost formation in lower level subsurface formations and cemented only to the lower level subsurface fonnations below the bottom of the permafrost formation. The entire weight of theinner well pipe is supported on the outer well pipe. In the event of subsequent subsidence of the permafrost: formation, the outer well pipe may subside without affecting the inner well pipe. A third inner well pipe is suspendible on and within the inner well pipe without causing buckling of the inner well pipe.

CEQTRALIZERS 5| PERMA FROST PRODUCTION FORMATION PATENTED FEB m l 8.561., 531

PERMA FROST CENTRALIZERS m 29 UCTION INVENTOR.

T N TERRELL V-MILLER,

BY /mm ATTORNEY.|

METHOD AND APPARATUS FOR LANDING WELL PIPE IN PERMAFROST FORMATIONS BACKGROUND OF THE INVENTION Field of the Invention The present invention concerns a method for landing well pipes in wells drilled through formations in which subsidence is likely to occur such as permafrost formation. The invention also concerns the arrangement of the well pipes-and equipment and material supporting the well pipe in accordance with that method.

Oil and gas wells drilled in the northern slope region of Alaska penetrate approximately 1,0001,500 feet of permafrost formations. Such formations are subject to thawing during drilling operations. Also, during the producing life of a well, heat from the produced fluids cause additional heat transfer to the permafrost formation. Over prolonged periods of time, the thawing may be of such extent that excessive ground subsidence may occur causing irreparable damage to the well pipes.

The present invention overcomes the problems in drilling and producing through permafrost formations by using a method that prevents damage from ground subsidence and resulting removal of formation lateral support for the well pipe strings.

SUMMARY THE INVENTION In brief, the method for landing and suspending well pipes comprises running and setting at least one outer well pipe in a permafrost formation; cementing said outer well pipe to said permafrost formation; running and setting at least one other inner well pipe through said permafrost formation and in said lower level subsurface formations; cementing said inner well pipe only to said lower level subsurface formations below the bottom of said pennafrost formation; and supporting the entire weight of said inner well pipe (full tension) on said outer well pipe in a manner such that said outer well pipe is permitted to move downwardly relative to said inner well pipe. The inner well pipe is prevented from buckling when the full weight of a third well pipe is supported within and on the inner well pipe. The invention also encompasses the arrangement of well pipe in accordance with this method.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the arrangementof well pipes in a well drilled through a permafrost formation landed and suspended in accordance with the method of the invention; and

FIG. 2 is an enlarged fragmentary view of one of the slip connections.

DESCRIPTION OF THE PREFERRED EMBODIMEN'IS Referring to the drawings, there is shown a well drilled through a permafrost formation 1 l and other lower subsurface formations 12 and having well pipes landed, suspended and cemented therein as follows. For purposes of discussion particular well pipe sizes and easing head sizes will be used; however, such sizes are not restrictive and the invention, it will be clear, will apply to any combination of sizes of well pipe.

Well 10 is drilled initially a sufficient distance to accommodate a 28-inch conductor casing pipe 15 and a -inch surface casing pipe 16. These well pipes are set and cemented to formation 11 and to each other by cement 17. A 20-inch casing head 18 is attached to casing pipe 16 while drilling through permafrost formation 11 and extending well 10 far enough below the bottom of the permafrost formation designated 8 to provide a preselected sufficient length of a supporting cement column 20. A 13%-inch protection casing pipe 21 is run and cemented in place only at the bottom as shown by cement column 20. The full weight of easing pipe 21 is set on only slips 22 (with no seal) in casing head 18. Well 10 is drilled deeper into a production formation to accommodate a 9%-inch oil pipe string 28. A separate 12-inch casing head 25 is attached to the upper end of easing pipe 21. Slips 26 and a seal 27 in casing head 25 support and seal oil pipe string 28 which is fully suspended on casing head 25 and is cemented only at the bottom by cement 29. Additional well pipes indicated by tubing 30 may be run and suspended from casing head 25. Rigid centralizers 31 may be arranged on conductor pipe 28 in the an nulus between casing pipe 21 to aid in preventing buckling of 0 casing pipe 21.

After casing pipe string 21 is run and cemented in by means of cement column 20, it is set with its entire weight supported on slips 22 (in full tension). After well pipe string 28 is run and cemented in place by means of cement 29, it isset with its entire weight plus additional tension supported on slips 26 arranged in casing head 25. The additional tension is required so as to always maintain tension in well pipe 28 after casing pipe 21 and easing head 25 reach a stable position upon subsidence of easing head 18 and complete transfer of the weight of well pipe string 28 and easing pipe string 21 from slips 22 to cement column 20. In this manner, pipe string 28 is suspended on, for example, l,0O0-l,500 feet of nonlaterally supported casing pipe 21 without buckling casing pipe 21.

The procedure in which casing pipe 21 is suspended by casing head 18 and easing pipe 16 with slips only allows casing pipe 21 to be set and held in full tension while drilling to total depth. In addition, downward movement of easing pipe 16 is permitted without pulling casing pipe 21 with it should ground subsidence occur.

It is to be noted that in accordance with the method described above, no cement is used around the top of casing pipe 21. That pipe is only cemented below the bottom of the permafrost formation B. Further, no cement is used between casing pipe 21 and easing pipe 16 and except for the cement used to cement in casing pipe 16 and conductor casing pipe 15, there is no cement used above the bottom B of the permafrost formation. Cementing in this manner permits independent vertical movement of easing pipes 16 and 21.

I claim:

1. A method for landing and suspending well pipes in a well penetrating subsurface formations including a permafrost formation that prevents damage from ground subsidence and removal of formation lateral support comprising:

forming said well in said permafrost formation;

setting a first well pipe and a second well pipe of lesser diameter than said first well pipe in said permafrost formation;

cementing said first and second well] pipes together and to said permafrost formation;

attaching a first casing head to said second well pipe;

extending said well to below said permafrost formation;

running a third well pipe into said well through said first casing head;

cementing said third well pipe to a. subsurface formation only at the bottom of said third well pipe and only below said permafrost formation;

supporting the entire weight of said third well pipe on said second well pipe in a manner such that said second well pipe is movable downwardly relative to said third well att ghing a second casing head to said third well pipe;

running a fourth well pipe through said second casing head;

cementing said fourth well pipe only on the bottom of said fourth well pipe in said well; and

setting said fourth well pipe with the entire weight of said fourth well pipe supported on said second casing head.

2. A method as recited in claim 1 in which said third well pipe is supported on said second well pipe by means of first slips and said fourth well pipe is supported on said second casing head by means of second slips.

3. A method as recited in claim 2 including setting said fourth well pipe with the entire weight of said fourth well pipe plus additional tension supported on said second slips.

4. A method as recited in claim 3 in which said additional tension is sufficient to always maintain tension is said fourth well pipe after said third well pipe and second casing head reach a stable position upon subsidence of said first casing head and complete transfer of the weight of said fourth well pipe and third well pipe from said first slips to the cement cementing said third well pipe in said well.

5. A method as recited in claim 4 including arranging centralizers on the outer surface of said fourth well pipe to aid in preventing buckling of said third well pipe.

6. A method for landing and suspending well pipe in a well drilled through a permafrost formation into lower level subsurface formations comprising:

running and setting at least one outer well pipe in said permafrost formation;

cementing said outer well pipe to said permafrost formation;

running and setting at least one other inner well pipe through said permafrost formation and in said lower level subsurface formations;

cementing said inner well pipe only to said lower level subsurface formations below the bottom of said permafrost formation; and

supporting the entire weight of said inner well pipe on said outer well pipe in a manner such that said outer well pipe is permitted to move downwardly relative to said inner well pipe.

7. A method for landing and suspending well pipe in a well drilled through a permafrost formation into lower level subsurface formations comprising:

running and setting an outer well pipe in said permafrost formation;

cementing said outer well pipe to a said permafrost formation; running and setting an inner well pipe through said permafrost formation and in said lower level subsurface formation;

cementing said inner well pipe only to said lower level sub surface formations below the bottom of said permafrost formation;

supporting the entire weight of said inner well pipe on said outer well pipe in a manner such that said outer well pipe is permitted to move downwardly relative to said inner well pipe;

running and setting another inner well pipe through said permafrost formation and in said lower level subsurface formation; and

cementing said other inner well pipe only on the bottom of said other inner well pipe in said well, said other inner well pipe in said well, said other inner well pipe being set with the entire weight of said other inner well pipe plus additional tension supported on said outer well pipe and said additional tension being sufficient to always maintain tension in said other inner well pipe after said inner well pipe has reached a stable position upon subsidence of said outer well pipe and complete transfer of the weight of said other inner well pipe and said inner well pipe to the cement cementing said inner well pipe in said well.

8. A method as recited in claim 7 in which said inner well pipe is supported on said outer well pipe by means of first slips and said other inner well pipe is supported by means of second slips.

9. A method as recited in claim 8 including arranging centralizer means of the outer surface of said other inner well pipe to aid in preventing buckling of said inner well pipe.

10. A system of landed and suspended well pipes in wells drilled through a permafrost formation into subsurface formations to prevent damage from ground subsidence and resultant removal of formation lateral support comprising:

a first well pipe set in said permafrost formation;

a second well pipe smaller in diameter than said first well pipe set in said permafrost formation and cemented to said first well pipe and to said permafrost formation;

a first casin head attached to said second well gipe' a third wel pipe attached to said first casing cad and, ex-

tending to below said permafrost formation and cemented to subsurface formations only below the bottom of said permafrost formation, said third well pipe being supported from said in a manner such that said second well pipe is moveable downwardly relative to said third well pipe;

a second casing head attached to said third well pipe; and

a fourth well pipe suspended from said second casing head and cemented to subsurface formations only below the bottom of said permafrost formation.

11. A system as recited in claim 10 including slips for supporting the entire weight of said third well pipe on said second well pipe.

12. A system as recited in claim 11 including additional slips for suspending said fourth well pipe from said second casing head.

13. A system as recited in claim 12 including centralizer means arranged on said fourth well pipe for aiding in preventing buckling of said third well pipe.

14. An arrangement of well pipes landed and suspended in wells drilled through a permafrost formation into subsurface formations comprising:

at least one well pipe set and cemented in said permafrost formation;

at least one other well pipe smaller in diameter than said first well pipe set through said permafrost formation and in said lower level subsurface formations below said permafrost formation, said other well pipe being cemented only to said lower level subsurface formation below the bottom of said permafrost formation;

means for supporting said other well pipe on said one well pipe in a manner such that said one well pipe is movable downwardly relative to said other well pipe.

15. An arrangement of well pipes landed and suspended in wells drilled through a permafrost formation into subsurface formations comprising:

one outer well pipe set and cemented into said permafrost formation; one inner well pipe set through said permafrost formation and into said lower level subsurface formations, said inner well pipe being cemented only to said lower level formations below the bottom of said permafrost formation;

means for supporting the entire weight of said inner well pipe on said outer well pipe in a manner such that said outer well pipe is moveable downwardly relative to said inner well pipe;

another inner well pipe set through said permafrost formation and into said lower level subsurface formations, said other inner well pipe being cemented only to said lower level subsurface fonnations below the bottom of said permafrost formation; and

means for supporting the entire weight of said other inner well pipe plus additional tension on said inner well pipe.

16. An arrangement as recited in claim 15 including slips supporting said inner well pipe on said outer well pipe;

17. An arrangement as recited in claim 16 including additional slips supporting said other inner well pipe on said inner well pipe.

18. An arrangement as recited in claim 17 in which said additional tension is sufficient to always maintain tension in said other inner well pipe after said inner well pipe reaches a stable position upon subsidence of said outer well pipe and complete transfer of weight of said other inner well pipe and inner well pipe from said slips to the cement cementing said inner well pipe into said well.

19. An arrangement as recited in claim 18 including centralizer means arranged on said other inner well pipe to aid in preventing buckling of said inner well pipe.

20. An arrangement as recited in claim 19 in which said slips and said additional slips are directed in an upward direction only. 

1. A method for landing and suspending well pipes in a well penetrating subsurface formations including a permafrost formation that prevents damage from ground suBsidence and removal of formation lateral support comprising: forming said well in said permafrost formation; setting a first well pipe and a second well pipe of lesser diameter than said first well pipe in said permafrost formation; cementing said first and second well pipes together and to said permafrost formation; attaching a first casing head to said second well pipe; extending said well to below said permafrost formation; running a third well pipe into said well through said first casing head; cementing said third well pipe to a subsurface formation only at the bottom of said third well pipe and only below said permafrost formation; supporting the entire weight of said third well pipe on said second well pipe in a manner such that said second well pipe is movable downwardly relative to said third well pipe; attaching a second casing head to said third well pipe; running a fourth well pipe through said second casing head; cementing said fourth well pipe only on the bottom of said fourth well pipe in said well; and setting said fourth well pipe with the entire weight of said fourth well pipe supported on said second casing head.
 2. A method as recited in claim 1 in which said third well pipe is supported on said second well pipe by means of first slips and said fourth well pipe is supported on said second casing head by means of second slips.
 3. A method as recited in claim 2 including setting said fourth well pipe with the entire weight of said fourth well pipe plus additional tension supported on said second slips.
 4. A method as recited in claim 3 in which said additional tension is sufficient to always maintain tension is said fourth well pipe after said third well pipe and second casing head reach a stable position upon subsidence of said first casing head and complete transfer of the weight of said fourth well pipe and third well pipe from said first slips to the cement cementing said third well pipe in said well.
 5. A method as recited in claim 4 including arranging centralizers on the outer surface of said fourth well pipe to aid in preventing buckling of said third well pipe.
 6. A method for landing and suspending well pipe in a well drilled through a permafrost formation into lower level subsurface formations comprising: running and setting at least one outer well pipe in said permafrost formation; cementing said outer well pipe to said permafrost formation; running and setting at least one other inner well pipe through said permafrost formation and in said lower level subsurface formations; cementing said inner well pipe only to said lower level subsurface formations below the bottom of said permafrost formation; and supporting the entire weight of said inner well pipe on said outer well pipe in a manner such that said outer well pipe is permitted to move downwardly relative to said inner well pipe.
 7. A method for landing and suspending well pipe in a well drilled through a permafrost formation into lower level subsurface formations comprising: running and setting an outer well pipe in said permafrost formation; cementing said outer well pipe to a said permafrost formation; running and setting an inner well pipe through said permafrost formation and in said lower level subsurface formation; cementing said inner well pipe only to said lower level subsurface formations below the bottom of said permafrost formation; supporting the entire weight of said inner well pipe on said outer well pipe in a manner such that said outer well pipe is permitted to move downwardly relative to said inner well pipe; running and setting another inner well pipe through said permafrost formation and in said lower level subsurface formation; and cementing said other inner well pipe only on the bottom of said other inner well pipe in said well, said other inner well pipe in said well, said other inner well pipe being set with the entire weight of said other inner well pipe plus additional tension supported on said outer well pipe and said additional tension being sufficient to always maintain tension in said other inner well pipe after said inner well pipe has reached a stable position upon subsidence of said outer well pipe and complete transfer of the weight of said other inner well pipe and said inner well pipe to the cement cementing said inner well pipe in said well.
 8. A method as recited in claim 7 in which said inner well pipe is supported on said outer well pipe by means of first slips and said other inner well pipe is supported by means of second slips.
 9. A method as recited in claim 8 including arranging centralizer means of the outer surface of said other inner well pipe to aid in preventing buckling of said inner well pipe.
 10. A system of landed and suspended well pipes in wells drilled through a permafrost formation into subsurface formations to prevent damage from ground subsidence and resultant removal of formation lateral support comprising: a first well pipe set in said permafrost formation; a second well pipe smaller in diameter than said first well pipe set in said permafrost formation and cemented to said first well pipe and to said permafrost formation; a first casing head attached to said second well pipe; a third well pipe attached to said first casing head and extending to below said permafrost formation and cemented to subsurface formations only below the bottom of said permafrost formation, said third well pipe being supported from said in a manner such that said second well pipe is moveable downwardly relative to said third well pipe; a second casing head attached to said third well pipe; and a fourth well pipe suspended from said second casing head and cemented to subsurface formations only below the bottom of said permafrost formation.
 11. A system as recited in claim 10 including slips for supporting the entire weight of said third well pipe on said second well pipe.
 12. A system as recited in claim 11 including additional slips for suspending said fourth well pipe from said second casing head.
 13. A system as recited in claim 12 including centralizer means arranged on said fourth well pipe for aiding in preventing buckling of said third well pipe.
 14. An arrangement of well pipes landed and suspended in wells drilled through a permafrost formation into subsurface formations comprising: at least one well pipe set and cemented in said permafrost formation; at least one other well pipe smaller in diameter than said first well pipe set through said permafrost formation and in said lower level subsurface formations below said permafrost formation, said other well pipe being cemented only to said lower level subsurface formation below the bottom of said permafrost formation; means for supporting said other well pipe on said one well pipe in a manner such that said one well pipe is movable downwardly relative to said other well pipe.
 15. An arrangement of well pipes landed and suspended in wells drilled through a permafrost formation into subsurface formations comprising: one outer well pipe set and cemented into said permafrost formation; one inner well pipe set through said permafrost formation and into said lower level subsurface formations, said inner well pipe being cemented only to said lower level formations below the bottom of said permafrost formation; means for supporting the entire weight of said inner well pipe on said outer well pipe in a manner such that said outer well pipe is moveable downwardly relative to said inner well pipe; another inner well pipe set through said permafrost formation and into said lower level subsurface formations, said other inner well pipe being cemented only to said lower level subsurface formations below the bottom of said permafrost formation; and means for supporting the entire weight of said other inner well pipe plus additional tension on said inner well pipe.
 16. An arrangement as recited in claim 15 including slips supporting said inner well pipe on said outer well pipe.
 17. An arrangement as recited in claim 16 including additional slips supporting said other inner well pipe on said inner well pipe.
 18. An arrangement as recited in claim 17 in which said additional tension is sufficient to always maintain tension in said other inner well pipe after said inner well pipe reaches a stable position upon subsidence of said outer well pipe and complete transfer of weight of said other inner well pipe and inner well pipe from said slips to the cement cementing said inner well pipe into said well.
 19. An arrangement as recited in claim 18 including centralizer means arranged on said other inner well pipe to aid in preventing buckling of said inner well pipe.
 20. An arrangement as recited in claim 19 in which said slips and said additional slips are directed in an upward direction only. 